[webkit-dev] XHR responseArrayBuffer attribute

[Maciej Stachowiak]

On Sep 28, 2010, at 7:15 AM, Chris Marrin wrote:

> 
> On Sep 27, 2010, at 6:37 PM, Maciej Stachowiak wrote:
> 
>> 
>> On Sep 27, 2010, at 3:19 PM, Michael Nordman wrote:
>> 
>>> Webkit's XHR currently does not keep two copies of the data that I can see. I think we should avoid that.
>> 
>> We could keep the raw data around, which hopefully is directly usable as an ArrayBuffer backing store, and only translate it to text format when/if the client requests responseText. 
> 
> Yes, the raw data should be usable without translation in an ArrayBuffer. But we'd still need to make a copy of the raw bits when a new ArrayBuffer is created via responseArrayBuffer(), because that object is mutable.

Is there an immutable variant of ArrayBuffer? If not, we really need one. But even without that, note that you don't necessarily need to make an immediate copy, you can use copy-on-write.

The immutable variant would be helpful since we could avoid implementing threadsafe copy-on-write just to allow efficient passing of ArrayBuffers to Workers.

Regards,
Maciej